Re: 64-bit jiffies, a better solution

[george anzinger <george@mvista.com>]

Jim Houston wrote:
> 
> Hi!
> 
> First what problem are you trying to solve?
> Why not have both variables and if they happen
> to endup in the same cache line you probably
> need years worth of jiffies to notice how
> long one more add takes.  E.g.
> 
>         jiffies_64++;
>         jiffies++;
> 
> To round out the list of options, how about a few lines of
> inline asm?  Maybe something like:
> 
>    extern unsigned long long jiffie_64;
>    extern unsigned int jiffie;
>    __asm__ (" \
>         .data
>         .align  8
>         .global jiffie
>         .global jiffie_64
>         .type   jiffie,@object
>         .size   jiffie,4
>         .type   jiffie_64,@object
>         .size   jiffie_64,8
>    jiffie_64:
>    jiffie:
>         .long   0, 0
>    ");
> 
> Adding the obvious ifdef of course.  Aside for broken
> binutils this might be portable code :-)

Until you move to a big endian 32-bit machine.  I would much rather hear
IS portable.
-- 
George Anzinger   george@mvista.com
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Real time sched:  http://sourceforge.net/projects/rtsched/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml